Peter Attia

You should probably have two 45-minute high intensity workouts.

But when I talk about training, and maybe I should be, but I'm generally not talking to that population.

When I'm talking to my patients in that population, it's a different story.

And we do.

We're very clear that if you've only got two and a half hours this week to exercise, we're going to craft your program around that.

But I'm talking to a person who is really thinking about how to optimize and achieve their best results over both lifespan and health span over decades.

And if that's the case, then you're going to need more volume than 150 minutes a week.

And then that means you're going to have to utilize different levels of intensity.

So because zone two is this point at which lactate rises to the level where it's now in the bloodstream, so local tissues can't clear it, but your body is able to clear it.

You're stressing the system.

This is the first place where you're now really stressing the system enough to recruit more glycolytic fibers.

But what's nice about this is the intensity is low enough that you can keep going for a long enough period of time.

And this is why endurance athletes who are training for 15 to 20 hours a week are indeed spending basically 80% of their time in this zone.

because the intensity is low enough that they can do it for so long, and yet they are still getting a training adaptation.

So if you are training in zone two, while you're not getting as much adaptation as you're getting at zone five, you're still applying a strong enough training stimulus to activate both fuel systems, right?

So you're not maximal, but you're near maximal for fat oxidation.

You have some glycolysis, you have lactate shuttle,

But you don't have the wear and tear of the acidity and the fatigue that comes when lactate production completely overwhelms clearance systemically.

So again, you can pack in volume of training in a way that you can't with very high intensity.

There are other benefits to zone two, by the way, if you're an athlete, which is it comes with the benefits of improved movement efficiency.